Optimizing Vegetable Production Under Hoophouses In High Desert Environments

Consumer demands for fresh, locally-grown food that is produced in an environmentally responsible and sustainable manner have increased greatly in the high desert environment of Nevada. Consumers are willing to pay premium prices for produce delivered at the height of freshness, and farmers have responded to this demand by an explosion of hoophouse construction during the last four years.

Existing guidance for hoophouse construction has been useful, but high winds in desert environments have caused several structural failures, and guidance for which products are appropriate for hoophouse production in high desert environments is inadequate, particularly during off-season months when demand for fresh produce is especially high. Furthermore, although hoophouse production is reputed to improve agricultural sustainability over field production, little data exist to confirm the claims for high desert environments.

Our project will document water use efficiencies of vegetable production at the Nevada Agricultural Experiment Station Valley Road Field Laboratory and at the High Desert Farming Initiative by production season; experimentally manipulate water stress, mechanical stress, and light stress to determine interrelationships among plant growth conditions and bioactive nutritional content to improve product taste and quality; and monitor pest and disease problems.

Our program will deliver guidelines for producers to optimize vegetable production in high desert environments and peer-reviewed, research-based manuscripts that document sustainable and successful hoophouse production systems.

Our project involves experienced academic researchers, educators, and extension specialists who will actively collaborate with successful producers. Because many farmers and ranchers in Nevada are looking for ways to diversity their operations, our results potentially may impact nearly all the over 3000 principal farms and almost 5000 operators in Nevada plus additional farms in surrounding states with high desert environments.

The high desert climate of Nevada has potential for sustainable food production, with generally warm temperatures, abundant sunshine, and well-developed irrigation delivery systems. However, the extremely dry air masses and mountain terrain lead to very high evaporative demand, and large night/day and seasonal temperature fluctuations result in potential for both early-season and late-season frosts that limit production of frost-sensitive vegetable crops.

Hoophouse production has potential to improve these climate conditions and allow producers to maximize water, energy, and solar radiation efficiencies to produce sustainable crops. As season extenders, hoophouses have potential to provide producers with premium sales revenues. However, evidence to support these potentials in high desert environments is meager.

Consumers in Nevada and elsewhere are increasingly interested in diets that include more fresh vegetables and fruits, which are sources of bioactive nutrients with significant health. The bioactive nutrient content of vegetables and fruits is influenced by several key factors including genotype selection and environmental conditions (light, temperature, humidity, etc.). Consumer interest in the content of health promoting compounds is becoming a vital consideration for fruits and vegetable growers.

Fortunately, plant-breeding programs have enhanced levels of carotenoids and other antioxidants, and nutritional quality of vegetables can be manipulated by changes in water, mechanical, and light stress. For example, growing stresses can be manipulated to increase level of anthocyanins, Vitamin C, carotenoids, anthocyanin, phenols, and other bioactive compounds. However, much of this research is experimental and guidelines for growers to implement practices are lacking. Furthermore, little is known about how such changes affect the consumer’s acceptability of these food products.

Therefore, we must examine not only nutrition quality of produce, but also consumer’s sensory perception of the different plant production methods in this project.

Intensive hoophouse vegetable production is reputed to improve agricultural sustainability over field-grown produce due to several factors, including: improved water/fertilizer use efficiencies, moderated climatic influences on crops, and increased profits to the agricultural producer. Unfortunately, little data from high desert environments exist to confirm these anecdotal observations.

Demand for fresh, locally-grown vegetables, which is predicated on health, nutritional quality, and food security concerns, has resulted in an explosion of hoophouse construction in Nevada during the past four years. In addition, economic opportunities for hoophouse production are also strong: Nevada imports $93.8 million of vegetables and melons and $195 million of fruits every year (Center for Economic Development, University of Nevada), and Las Vegas and Reno-Tahoe are world renowned tourist destinations with many high-end restaurants that emphasize food excellence.

Many of the recent hoophouse enterprises have not been in production long enough to determine if hoophouse technologies are durable or profitable for Nevada’s extreme weather conditions. In addition, systematic efforts are needed to determine which crops are best suited for hoophouse production in high desert environments and how hoophouse production should be managed to optimize appearance, taste, and bioactive nutritional content.

This project will help remedy the existing situation by evaluating critical components of intensive hoophouse vegetable production systems compared to field grown produce in the high desert environment of Nevada and by experimentally manipulating growth conditions in hoophouses to optimize production of desirable, nutritional vegetables. The components to be quantified include; vegetable production levels by season; water use efficiency; impacts of variations in solar radiation levels on production and bioactive nutritional content; and appearance, nutrition and taste profiles of selected vegetables.

The growth conditions to be experimentally manipulated include water stress, mechanical stress, and light stress. This information will be used to enhance existing outreach and educational programs to improve the sustainability of these systems in high desert environments.